Multi-layer body and process for the production of a multi-layer body

ABSTRACT

A multi-layer body having a partially shaped first layer and a diffractive first relief structure shaped in a first region of a replication layer. The first layer is applied to the replication layer in the first region and, in a second region, a photosensitive layer is applied to the first layer or a photosensitive washing mask is applied thereto as a replication layer. The photosensitive layer or the washing mask is exposed through the first layer so that the photosensitive layer or washing mask is exposed differently due to the first relief structure in the first and in the second regions, and the first layer is removed using the exposed photosensitive layer or washing mask as a mask layer in the first region but not in the second region or in the second region but not in the first region.

The invention concerns a multi-layer body having a replication layer andat least one partially shaped first layer arranged thereon in registerrelationship with a first relief structure, and a process for theproduction thereof.

Such components are suitable as optical components or also as lenssystems in the field of telecommunications.

GB 2 136 352 A describes a production process for the production of asealing film provided with a hologram as a security feature. In thatcase after the operation of embossing a diffractive relief structure aplastic film is metallised over its full area and then demetallised inregion-wise fashion in accurate register relationship with the embosseddiffractive relief structure.

Demetallisation in accurate register relationship is costly and thedegree of resolution which can be achieved is limited by the adjustmenttolerances and the procedure employed.

EP 0 537 439 B2 describes processes for the production of a securityelement with filigree patterns. The patterns are formed from diffractivestructures covered with a metal layer and surrounded by transparentregions in which the metal layer is removed. It is provided that theoutline of the filigree pattern is introduced in the form of adepression into a metal-coated carrier material, in that case at thesame time the bottom of the depressions is provided with the diffractivestructures and then the depressions are filled with a protectivelacquer. Excess protective lacquer is to be removed by a scraper blade.After application of the protective lacquer, it is provided that themetal layer is removed by etching in the unprotected transparentregions. The depressions are between about 1 μm and 5 μm while thediffractive structures can involve height differences of more than 1 μm.That process which, in repetition steps, requires adjustment steps fororientation in accurate register relationship, fails when dealing withfiner structures. In addition continuous metallic regions covering anarea are difficult to implement as the ‘spacers’ are missing, for theoperation of scraping off the protective lacquer.

The object of the present invention is to provide a multi-layer body anda process for the production of a multi-layer body, in which a layerwhich has regions in which the layer is not present can be applied inregister relationship with a high level of accuracy and inexpensively.

In accordance with the invention that object is attained by a processfor the production of a multi-layer body having a partially shaped firstlayer, wherein it is provided that a diffractive first relief structureis shaped in a first region of a replication layer of the multi-layerbody, that the first layer is applied to the replication layer in thefirst region and in a second region in which the relief structure is notshaped in the replication layer, with a constant surface density withrespect to a plane defined by the replication layer, that aphotosensitive layer is applied to the first layer or a photosensitivewashing mask is applied thereto as a replication layer, that thephotosensitive layer or the washing mask is exposed through the firstlayer so that the photosensitive layer or washing mask is exposeddifferently due to the first relief structure in the first and in thesecond regions, and that the first layer is removed using the exposedphotosensitive layer or washing mask as a mask layer in the first regionbut not in the second region or in the second region but not in thefirst region.

The object is further attained by a multi-layer body having areplication layer and at least one partially shaped first layer arrangedon the replication layer, wherein it is provided that a diffractivefirst relief structure is shaped in a first region of the replicationlayer, the first relief structure is not shaped in the replication layerin a second region of the replication layer, and the first layer ispartially removed in a manner determined by the arrangement of the firstrelief structure so that the first layer is removed in accurate registerrelationship with the first relief structure in the first region but notin the second region or in the second region but not in the firstregion.

The object is further attained by a process for the production of amulti-layer body having a partially shaped second layer wherein it isprovided that a diffractive first relief structure is shaped in a firstregion of a replication layer of the multi-layer body, a first layer isapplied to the replication layer in the first region and in a secondregion in which the relief structure is not shaped in the replicationlayer, with a constant surface density with respect to a plane definedby the replication layer, that a photosensitive layer or photosensitivewashing mask is exposed through the first layer so that thephotosensitive layer or washing mask is exposed differently due to thefirst relief structure in the first and in the second regions, and thatthe second layer is removed using the exposed photosensitive layer orwashing mask as a mask layer in the first region but not in the secondregion or in the second region but not in the first region.

The use of a multi-layer body according to the invention as an exposuremask for the production of a further multi-layer body with a partiallyshaped-out further layer is ideal. It is provided in that respect thatthe exposure mask has a replication layer, that a diffractive firstrelief structure is shaped in a first region of the replication layer,that the first relief structure is not shaped in the replication layerin a second region of the replication layer, and that a first layer isapplied to the replication layer in the first region and in a secondregion in which the first relief structure is not shaped in thereplication layer so that a photosensitive layer or photosensitivewashing mask exposed through the first layer is exposed differently inthe first and second regions due to the first relief structure.

The invention is based on the realisation that the diffractive reliefstructure in the first region influences physical properties of thefirst layer applied to the replication layer in that region, for exampleeffective thickness or optical density, so that the transmissionproperties of the first layer differ in the first and second regions.The first layer is now used in an exposure process as a ‘mask layer’ forpartial removal of the first layer itself by a procedure whereby aphotosensitive layer adjoining the first layer is exposed through thefirst layer—that is to say the functional layer. That affords theadvantage, over the mask layers applied with conventional processes,that the mask layer is oriented in accurate register relationshipwithout additional adjustment complication and expenditure. The firstlayer is an integral component part of the structure which is shaped inthe replication layer. Accordingly only the tolerances of that reliefstructure have an influence on the tolerances of the position of thefirst layer. A lateral displacement between the first relief structureand regions of the first layer with the same physical properties doesnot occur. The arrangement of regions of the first layer with the samephysical properties is exactly in register relationship with the firstrelief structure. Additional tolerances do not arise. The first layer isa layer which performs a dual function. On the one hand it implementsthe function of a highly accurate exposure mask for the productionprocedure while on the other hand at the end of the production procedureit forms a highly accurately positioned functional layer, for example anOVD layer or a conductor track or a functional layer of an electricalcomponent, for example an organic semiconductor component.

Furthermore it is possible to produce structured layers of very highresolution by means of the invention. The degree of registration andresolution which can be achieved is approximately better by a factor of100 than that which can be attained by known demetallisation processes.As the width of the structure elements of the first relief structure canbe in the region of the wavelength of visible light (between about 380and 780 nm) but also below same, it is possible to produce patternregions enjoying very fine contours. That means that in this respectalso great advantages are achieved in comparison with thedemetallisation processes used hitherto, and it is possible with theinvention to produce security elements with a higher level of safeguardagainst copying and forgery than hitherto.

It is possible to produce lines and/or dots with a high level ofresolution, for example of a width or of a diameter respectively of lessthan 5 μm, in particular to about 200 nm. Preferably levels ofresolution in the region of between about 0.5 μm and 5 μm, in particularin the region of about 1 μm, are achieved. In comparison, processeswhich involve adjustment in register relationship make it possible toimplement line widths of less than 10 μm, only at a very high level ofcomplication and expenditure.

The first layer is preferably applied to the replication layer by meansof sputtering, vapor deposition or spraying thereon. Due to theprocedure involved the sputtering operation involves a directedapplication of material so that, when applying material of the firstlayer by sputtering in a constant surface density with respect to theplane defined by the replication layer, to the replication layer whichis provided with the relief structure, the material is deposited locallyin differing thicknesses. At least partially directed application ofmaterial is preferably also produced, due to the procedure involved,when the first layer is applied by vapor deposition and spraying.

The multi-layer body can be a film element or a rigid body. Filmelements are used for example to provide documents, banknotes or thelike with security features. That can involve security threads for beingwoven into paper or for being introduced into a card, which can beformed with the process according to the invention with a partialdemetallisation in perfect register relationship with an OVD design.

Advantageously rigid bodies such as an identity card, a base plate for asensor element or a housing shell portion for a cell phone can also beprovided with the partially demetallised layers according to theinvention, which are in register relationship with functional structuresor with a diffractive design element. It can be provided that thereplication layer is introduced and structured directly with theinjection molding tool or by means of shaping with a punch or die usingUV lacquer. It can however also be provided that the method as set forthhereinbefore can be used to produce an exposure mask for producing afurther multi-layer body. An exposure mask according to the invention isdistinguished by a particularly high level of resolution which cannot beachieved with other mass production processes for security elements orthe like.

Such multi-layer bodies are suitable for example as optical componentssuch as lens systems, exposure and projection masks or as securityelements for safeguarding documents or ID cards, insofar as they covercritical regions of the document such as a passport picture or asignature of the owner or the entire document. They can also be used ascomponents or decoration elements in the field of telecommunications.

It has further proven to be desirable if the multi-layer body isarranged in the form of a security feature in a window of avalue-bearing document or the like. New security features with aparticularly brilliant and filigree appearance can be generated by meansof the process according to the invention. Thus it is possible forexample to produce images which are semi-transparent in thetransillumination mode by forming a rastering of the first layer.Furthermore it is possible for a first item of information to berendered visible in such a window in the reflection mode and for asecond item of information to be rendered visible in thetransillumination mode.

Advantageous configurations of the invention are set forth in theappendant claims.

It may advantageously be provided that the first layer is applied to thereplication layer over the full surface area, preferably by vapordeposition. Upon irregular application of the first layer, differencesin optical density can occur in regions which are provided with aconstant optical density, and a defective structure can be produced inthat way.

It can further be provided that the first layer is applied to thereplication layer in a thickness at which the first layer issubstantially opaque and is preferably of an optical density of greaterthan 1.5.

Surprisingly it has been found that the ratio of the transmissivities ofthe regions with a diffractive relief structure can be increased by anincrease in the opacity of the first layer. If thus exposure isimplemented with a corresponding strength of illumination through alayer which is usually identified as being opaque (for example anoptical density of 5) and which would normally not be used as a masklayer by virtue of its high optical density, particularly good resultscan be achieved.

It is of particular advantage if the first layer is applied to thereplication layer over the full surface area thereof in a thickness atwhich the first layer is of an optical density of between 2 and 7.

Advantageously it is provided that the first layer is formed by a metallayer or by a layer of a metal alloy. Such layers can be applied withtried-and-tested processes such as sputtering and they are already ofsufficient optical density when small layer thicknesses are involved.The first layer however can also be a non-metallic layer which forexample can be colored or doped, for example with nanoparticles or withnanospheres in order to increase their optical density.

It can further be provided that a second relief structure is shaped inthe replication layer in the second region and that shaped in thereplication layer as a first relief structure is a diffractive reliefstructure which increases the transmission of the first layer in thefirst region with respect to the transmission of the first layer in thesecond region. For that purpose the first structure can be produced witha greater relief depth than the second structure. It can further beprovided that the product of spatial frequency and relief depth of thefirst structure is greater than the product of spatial frequency andrelief depth of the second structure. It is also possible thereby thatthe configuration of the relief structure of the replication layer inthe first region and in the second region increases the transmission ofthe layer applied to the replication layer in the first region inrelation to the layer applied in the second region. The second reliefstructure can further be such that in the second region the interfacelayer between the replication layer and the first layer is substantiallyplanar.

To produce particularly great differences in terms of the opticaldensity of the first and the second relief structures, a diffractiverelief structure with a high depth-to-width ratio in respect of theindividual structure elements and in particular with a depth-to-widthratio of >0.3 can be shaped as the first relief structure in the firstregion and the second relief structure can be in the form of a reliefstructure with a low depth-to-width ratio.

With a suitable choice in respect of the layer thickness for the firstlayer, the use of special diffractive relief structures of that kindmakes it possible to generate very great differences, which are alreadydistinguishable with the eye, in the optical density of the first layerin the first region and in the second region. Surprisingly however itwas found that such great differences in transmission in the first andsecond regions are not compellingly necessary for implementation of theprocess according to the invention. Structures with slight differencesin the depth-to-width ratio also usually have relatively slightdifferences in transmission, when thin vapor deposition is involved.Even slight relative differences however can be strengthened by anincrease in the layer thickness of the first layer and thus the meanoptical density. Thus, good results can be achieved when the differencesin transmission of the first layer in the first and second regions arealready quite slight. The first layer can be a very thin layer of theorder of magnitude of some nm. The first layer applied with a uniformsurface density, with respect to the plane defined by the replicationlayer, is considerably thinner in regions with a high depth-to-widthratio than in regions with a low depth-to-width ratio.

The dimensionless depth-to-width ratio is a characteristic feature forenlarging the surface of preferably periodic structures, for example ofa sine-square configuration. The depth here is the spacing between thehighest and the lowest successive points of such a structure, that is tosay the spacing between a ‘peak’ and a ‘trough’. The spacing between twoadjacent highest points, that is to say between two ‘peaks’, is referredto as the width. Now, the higher the depth-to-width ratio, thecorrespondingly steeper are the ‘peak flanks’, and the correspondinglythinner is the first layer which is deposited on the ‘peak flanks’. Theeffect of producing a higher level of transmission and in particulartransparency with an increase in the depth-to-width ratio is alsoobserved in the case of structures with vertical flanks, for example inthe case of rectangular gratings. This however can also involvestructures to which this model cannot be applied. By way of example, thesituation may involve discretely distributed regions in line form, whichare only in the form of a ‘trough’, wherein the spacing between two‘troughs’ is a multiple greater than the depth of the ‘troughs’. Uponformal application of the above-specified definition the depth-to-widthratio calculated in that way would be approximately zero and would notreflect the characteristic physical condition. Therefore, in the case ofdiscretely arranged structures which are formed substantially only froma ‘trough’, the depth of the ‘trough’ is to be related to the width ofthe ‘trough’.

As it was surprisingly found, in that respect it is not important forthe regions with a high depth-to-width ratio to be transparent. This caninvolve structures which for example form optically active regions of ahologram or Kinegram® security feature. The only important considerationis that those regions are delimited in relation to other regions byvirtue of their transmission properties or a lesser or a greater opticaldensity.

It can advantageously be provided that the second relief structure is inthe form of an optically active, preferably diffractive structure. Thestructures which implement that are both reflecting and alsotransmitting light-diffracting, light-refracting or light-scatteringmicro- or nanostructures. That can involve for example gratingstructures such as linear gratings or cross gratings, image-generatingstructures such as a hologram or Kinegram®, isotropic or anisotropicmatt structures, binary or continuous Fresnel lenses, micro-prisms,micro-lenses, blaze gratings, combination structures, macrostructuresand so forth. After removal of the first layer in the first region thatoptically active structure is deposited in accurate registerrelationship with the first layer so that security features with a highforgery-resistant nature can be generated in that way.

The first and second relief structure can in that case involve reliefstructures, for example a Kinegram®, in which one or more reliefparameters, for example orientation, fineness or profile shape vary, inorder to produce the desired diffractive properties. The purpose ofstructures of that kind is not only to achieve a change in thetransmission properties of the first layer in the region in which therelief structure is shaped into the replication layer, but additionallyalso the function of acting as an optically variable design element uponbeing deposited with a reflection layer or an optical separation layer.If, besides a first relief structure of that kind, a second reliefstructure of that kind is also shaped in the replication layer, thefirst and relief structures preferably differ in one or more parameterswhich are relevant in terms of the transmission properties of the firstlayer, and thus differ for example in relief depth or in thedepth-to-width ratio. Thus it is possible for example for two Kinegram®security features to be shaped in the replication layer, in partiallyoverlapping relationship with a filigree line pattern. The firstKinegram® forms the first relief structure and the second Kinegram®forms the second relief structure. The relief structures of the twodesigns differ in the typical depth-to-width ratio while the otherstructure parameters are similar. We thus have three ‘groups’ ofstructures, namely structures of group I in the first Kinegram®,structures of group II in the second Kinegram® and structures of groupIII in the background. In a first step, the first layer remains, forexample a vapor-deposited metal layer such as a copper layer, while inthe Kinegram® region of the first design, the rest is removed. Thenanother material, for example aluminum, is vapor-deposited over theentire area and removed by suitable process implementation in thebackground regions. That procedure affords two designs which arepartially metallised in register relationship but which differ in themetal layer that faces towards the viewing person (copper, aluminum).

The process can further be such that a photosensitive material with abinary characteristic is applied as the photosensitive layer or as thephotosensitive washing mask and the photosensitive layer or thephotosensitive washing mask is exposed through the first layer in anexposure strength and with an exposure duration, the photosensitivelayer or the photosensitive washing mask is activated in the firstregion in which the transmission of the first layer is increased by thefirst relief structure and is not activated in the second region. Theprocess according to the invention can also be used if the opticaldensities of the first region and the second region differ only slightlyfrom each other, in which respect, as already explained hereinbefore, itis surprisingly possible to be based on a high mean optical density.

An advantageous configuration provides that the photosensitive layer orwashing mask is exposed through the first layer by means of UVradiation.

Experiments have demonstrated that the differences which can be achievedby virtue of the differing configuration of the relief structure in thefirst and second regions, in the transmission properties of the firstlayer, are particularly pronounced in the range of UV radiation.Particularly good results can thus be achieved when using UV radiationfor the exposure operation.

A photosensitive washing mask can be provided as the photosensitivelayer, in which respect the regions of the photosensitive washing maskwhich are activated by the exposure operation and the regions of thefirst layer which are arranged there are removed in a washing process.

The photosensitive layer however can also involve a layer which isdeveloped after the exposure operation and then forms an etching maskfor the first layer.

In addition there can be a photosensitive layer which is activated byexposure in the first region in which transmission of the first layer isenhanced by the first relief structure, and then forms an etching agentfor the first layer.

The photosensitive layer can be a photoresist which can be in the formof a positive or a negative photoresist. In that way different regionsof the first layer can be removed with the replication layer beingotherwise of the same nature.

It can further be provided that the photosensitive layer is in the formof a photopolymer.

By way of example lyes or acids can be provided as the etching agent forthe first layer. It can further be provided that the first layer is onlypartially removed and the etching operation is interrupted as soon as apredetermined degree of transparency is attained. That makes it possibleto produce for example security features which are based on locallydifferent transparency.

If for example aluminum is used as the first layer lyes such as NaOH orKOH can be used as an isotropically acting etching agent. It is alsopossible to use acid media such as PAN (a mixture of phosphoric acid,nitric acid and water).

The reaction speed typically increases with the concentration of the lyeand temperature. The choice of the process parameters depends on thereproducibility of the procedure and the resistance of the multi-layerbody.

Influencing factors when etching with lye are typically the compositionof the etching bath, in particular the concentration of etching agent,the temperature of the etching bath and the afflux flow conditions ofthe layer to be etched in the etching bath. Typical parameter ranges inrespect of the concentration of the etching agent in the etching bathare in the region of between 0.1% and 10% and in respect of temperaturein the region of between 20° C. and 80° C.

The etching operation for the first layer can be electrochemicallyassisted. The etching operation is intensified by the application of anelectrical voltage. The action is typically isotropic so that thestructure-dependent increase in surface area additionally intensifiesthe etching effect. Typical electrochemical additives such as wettingagents, buffer substances, inhibitors, activators, catalysts and thelike in order to remove for example oxide layers can promote the etchingprocedure.

During the etching procedure depletion of etching medium or enrichmentin respect of the etching products can occur in the interface layer inrelation to the first layer, whereby the etching speed is slowed down.Forced mixing of the etching medium, possibly by the production of asuitable flow or ultrasound excitation, improves the etchingcharacteristics.

The etching procedure can further involve a temperature profile inrespect of time in order to optimise the etching result. Thus etchingcan be effected in the cold condition at the beginning and warmer withan increasing period of operation. That is preferably implemented in theetching bath by a three-dimensional temperature gradient, in which casethe multi-layer body is drawn through an elongate etching bath withdifferent temperature zones.

The last nanometers of the first layer can prove to be relativelystubborn and resistant to etching in the etching procedure. Therefore,slight mechanical assistance for the etching process is advantageous forremoving the remains of the last layer. The stubbornness is based on apossibly slightly different composition in respect of the first layer,presumably by virtue of interface layer phenomena when the first layeris formed on the replication layer. In that case the last nanometers ofthe first layer are preferably removed by a wiping process by themulti-layer body being passed over a roller covered with a fine cloth.The cloth wipes off the remains of the first layer without damaging themulti-layer body.

The etching operation does not have to involve a finishing step which iscarried out with fluids. It can also be a ‘dry process’ such as forexample plasma etching.

In addition laser ablation has proved its worth for removing the firstlayer. In the case of structures with a high depth-to-width ratio and inparticular relief structures in which the typical spacing between twoadjacent raised portions is less than the wavelength of the incidentlight, so-called zero order structures, a large part of the incidentlight can be absorbed, even if the degree of reflection of thereflection layer, in a region involving mirror reflection, is high. Thefirst layer which is in the form of a reflection layer is irradiated bymeans of a focused laser beam, in which case the laser radiation isabsorbed to an increased extent and the reflection layer iscorrespondingly increased in temperature in the strongly absorbentregions which have the above-mentioned structures with a highdepth-to-width ratio. With high levels of energy input the reflectionlayer can locally spall off, in which case removal or ablation of thereflection layer or coagulation of the material of the reflection layeroccurs. If energy input by the laser is effected only over a shortperiod of time and the effect of thermal conduction is thus only slight,ablation or coagulation occurs only in the regions which are pre-definedby the relief structure.

Influencing factors in laser ablation are the configuration of therelief structure (period, depth, orientation, profile), the wavelength,polarisation and angle of incidence of the incident light radiation, theduration of the action (time-dependent power) and the local dose oflaser radiation, the properties and the absorption characteristics ofthe first layer, as well as the first layer possibly having furtherlayers covering it above it or below it, such as the structuredphotosensitive or washing lacquer layer.

Inter alia Nd:YAG lasers have proven to be suitable for the lasertreatment. They emit at about 1064 mm and are preferably also operatedin a pulsed mode. It is further possible to use diode lasers. Thewavelength of the laser radiation can be altered by means of a frequencychange, for example frequency doubling.

The laser beam is guided over the multi-layer body by means of aso-called scanning device, for example by means of galvanometric mirrorsand a focusing lens. Pulses of a duration in the region of nanosecondsto microseconds are emitted during the scanning operation and lead tothe above-described ablation or coagulation of the first layer, as ispredetermined by the structure. The pulse durations are typically belowmilliseconds, advantageously in the region of a few microseconds orless. It is thus certainly also possible to use pulse durations ofnanoseconds to femtoseconds. Precise positioning of the laser beam isnot necessary as the procedure is self-referencing insofar as thephotosensitive layer or washing mask, which is present in structuredform, partially prevents access of the laser radiation to the firstlayer. The procedure is preferably further optimised by a suitablechoice in respect of the laser beam profile and overlapping of adjoiningpulses.

It is however equally possible to control the path of the laser over themulti-layer body in register relationship with relief structuresdisposed in the replication layer or openings in the photosensitivelayer or washing mask, so that only regions with the same reliefstructure or with/without openings in the photosensitive layer orwashing mask are irradiated. For example camera systems can be used forsuch control.

Instead of a laser which is focused on to a point or a line it is alsopossible to use areal radiating devices which emit a short, controlledpulse such as for example flash lights.

The advantages of the laser ablation process include inter alia the factthat the partial removal of the first layer, in register relationshipwith a relief structure, can also take place if it is covered on bothsides with one or more further layers which are transmissive in respectof the laser radiation, and it is thus not directly accessible toetching media. The first layer is only broken up by the laser. Thematerial of the first layer breaks off again in the form of smallconglomerates or small balls which are not optically visible to theviewing person and which only immaterially influence the transparency inthe irradiated region.

Residues from the first layer which have still remained on thereplication layer after the laser treatment can optionally be removed bymeans of a subsequent washing procedure if the first layer is directlyaccessible.

After etching of the first layer it can be provided that the residues ofthe etching masks are removed.

In a further advantageous configuration a second layer can be introducedinto the regions in which the first layer has been removed. It canfurther be provided that the first layer is removed and replaced by athird layer. The process according to the invention is therefore notrestricted to the partial removal of a layer but it can have furtherprocess steps which provide for the interchange of layers or therepetition of process steps when using differences in optical densityfor forming or differentiating regions.

It can further be provided that the first layer and/or the second layerand/or the third layer are galvanically reinforced if these involveelectrically conductive layers or layers which are suitable forcurrent-less galvanisation.

For a multi-layer body produced in accordance with the described processit can be provided that the second region comprises two or more partialregions enclosed by the first region, an optically active second reliefstructure is shaped in the replication layer in the second region andthe first layer is a reflection layer which is removed in the firstregion and thus arranged in accurate register relationship with thesecond relief structure. Such multi-layer bodies can advantageously beprovided as forgery-resistant security elements. They are alreadyparticularly forgery-resistant for the reason that particularly smallline widths can be formed with the process according to the invention.

In addition, because of their diffractive structure and theirorientation in relation to the reflection layer in accurate registerrelationship, those fine lines can produce optical effects which can beimitated only with extreme difficulty. The multi-layer body can involvefor example a transfer film, in particular a hot stamping film or alaminating film.

It can further be provided that the first region comprises two or morepartial regions enclosed by the second region or vice-versa and that thefirst layer is a reflection layer which is removed in the second regionand thus arranged in accurate register relationship with the firstrelief structure.

Advantageous configurations provide that the partial regions of thesecond region or the partial regions of the first region are of a widthof less than 2 mm, preferably less than 1 mm.

Further configurations provide that, in the multi-layer body accordingto the invention, a second layer is arranged in the regions of thereplication layer in which the first layer has been removed.

It can be provided that the first layer and/or the second layer is/areformed from a dielectric, for example TiO₂ or ZnS, or a semiconductor.In that case the first layer and the second layer have differentrefractive indices so that optical effects can be produced thereby.

The first layer and/or the second layer can also involve a polymer sothat for example the one layer can be in the form of an electricalconductor and the other layer can be in the form of an electricalinsulator, in which respect both layers can be in the form oftransparent layers.

By way of example the first layer and/or the second layer can form anelectronic component, for example an antenna, a capacitor, a coil or anorganic semiconductor component. As explained hereinbefore it ispossible to provide further layers which can be arranged in accurateregister relationship on the multi-layer body with the process accordingto the invention.

It can also be provided that the succession of partial removal of layersor partial demetallisations and the association with the structures inthe first and second regions is so selected that regions are produced,in which different diffractive structures are interlaced with eachother. This may involve for example a first Kinegram® and a secondKinegram® which have a different depth-to-width ratio and which arearranged in front of a background. In that example it can be providedthat a vapor-deposited copper layer is left only in the region of thefirst Kinegram® security feature, then aluminum is applied by vapordeposition over the entire surface area and removed in the backgroundregions by suitable process implementation. That produces two designswhich are partially metallised in register relationship and which differin the metal layer which faces towards the viewing person.

The relief structures introduced into the replication layer can also beso selected that they can serve for orientation of liquid crystal(polymers). Thus in that case the replication layer and/or the firstlayer can be used as an orientation layer for liquid crystals. Forexample structures in groove form are introduced into such orientationlayers, wherein the liquid crystals are oriented in relation to suchstructures before they are fixed in their orientation in that positionby crosslinking or in some other fashion. It can be provided that thecrosslinked liquid crystal layer forms the second layer.

The orientation layers can have regions in which the orientationdirection of the structure constantly changes. If a region formed bymeans of such a diffractive structure is viewed through a polariser withfor example a rotating direction of polarisation, various clearlydiscernible security features, for example motion effects, can thus beproduced by virtue of the linearly changing direction of polarisation ofthe region. It can also be provided that the orientation layer hasdiffractive structures for orientation of the liquid crystals, which arelocally differently oriented so that the liquid crystals when consideredunder polarised light represent an item of information such as forexample a logo.

It can also be provided that the first layer and/or the second layeris/are in the form of a colored layer.

Colored regions can also be produced in accordance with the processdescribed hereinafter. A multi-layer body is produced by means of theprocess according to the invention, using a colored photosensitive layeror washing mask. Coloring can be effected in that case by means ofpigments or soluble dyestuffs.

Then the photosensitive layer is exposed through the first layer, bymeans for example of UV radiation, and hardened or destroyed in thefirst regions, depending on whether it is a positive or the negativeresist. In that case positive and negative resist layers can also beapplied in mutually juxtaposed relationship and exposed at the sametime. In that case the first layer serves as a mask and is preferablyarranged in direct contact with the photoresist so that precise exposurecan be effected.

Finally, when developing the photoresist, the regions which have notbeen hardened are washed off or the destroyed regions are removed.Depending on the respective photoresist used the developed coloredphotoresist is now either present precisely in the regions in which thefirst layer is transparent or opaque in relation to the UV radiation. Inorder to increase the resistance of the photoresist layer which hasremained and which is structured in accordance with the first layer,regions which have remained are preferably post-hardened after thedevelopment operation.

Finally the first layer which is used as the mask can be removed by afurther etching step to such an extent that the multi-layer body onlyhas a highly resolved ‘color print’ of photoresist for the viewingperson, but is otherwise transparent. In that situation the photoresistfunctions as an etching mask.

Advantageously, display elements of high resolution can be produced inthat way. Without departing from the scope of the invention it ispossible for differently colored display elements to be applied inaccurate register relationship and for them to be arranged for examplein an image dot raster. As different multi-layer bodies can be producedwith an initial layout in respect of the first layer, by a procedurewhereby for example different exposure and etching processes arecombined together or are carried out in succession, positioning inaccurate register relationship of the successively applied layers ispossible when using the process according to the invention, in spite ofan increase in the process steps.

Further optical effects can be produced if the first layer and/or thesecond layer is/are formed from a plurality of partial layers, inparticular if the partial layers form a thin film layer system.

It can be provided that the partial layers are formed from differentmaterials. Such a configuration can be provided not just for theabove-mentioned thin film layer system. In that way for examplenanotechnology function elements can also be produced, for example abimetal switch involving dimensions in the μm range can be produced fromtwo different metallic layers.

In further configurations it can be provided that the first layer and/orthe second layer forms/form an optical pattern. This can involve araster image.

Rastering of the first layer is also possible to the effect that, besideraster elements which are underlaid with a reflection layer and whichhave possibly different diffractive diffraction structures, there areprovided raster elements which represent transparent regions without areflection layer. In that respect amplitude-modulated or area-modulatedrastering can be selected as the rastering effect. Attractive opticaleffects can be achieved by a combination of such reflective/diffractiveregions and non-reflective, transparent—under some circumstances alsodiffractive—regions. If such a raster image is arranged for example in awindow in a value-bearing document, a transparent raster image can beperceived in the transillumination mode. In the incident illuminationmode that raster image is visible only in a given angular range in whichno light is diffracted/reflected by the reflecting surfaces. It isfurther possible for such elements to be used not only in a transparentwindow but also to be applied to a colored imprint. In a given angularrange the colored imprint is visible for example in the form of theraster image while in another angular range it is not visible by virtueof the light which is reflected by the diffraction structures or other(macro-) structures. Furthermore it is also possible for a plurality ofoutgoing reflection regions which decrease in their reflectivity to beproduced by a suitably selected rastering effect.

It can also be provided that the first layer is not completely removed,but its layer thickness is merely reduced. Such a configuration can beparticularly advantageous if regions are to be produced which havemutually superposed layers, for example in order to vary optical and/orelectrical properties or to produce decorative effects.

In the above-described process of using an exposure mask with areplication layer and a first layer in order to structure the secondlayer, it can be provided that the replication layer is applied to acarrier layer of an exposure mask.

That process can preferably also be combined with the above-describedfurther steps, that is to say the process of claim 46 can be combined inthe same manner as the process of claim 1 with the further features ofclaims 2 through 25. That also applies to the exposure mask as set forthin claim 51 which is used in the process.

It can further be provided that the photosensitive layer orphotosensitive washing mask is arranged on the second layer and isexposed through the second layer. As already described hereinbefore forthat purpose the second layer does not have to be in the form of atransparent layer. The second layer can be in the form of an opaquelayer for it reduces the illumination intensity in all regions of thephotosensitive layer or the photosensitive washing mask to the samedegree. Therefore the differences in the exposure mask in terms ofoptical density are retained and a true representation of the exposuremask is produced on the photosensitive layer or the photosensitivewashing mask. When using a washing mask it can be provided that thesecond layer is arranged on the washing mask as the final lowermostlayer so that the second layer is not arranged in the beam path betweenthe exposure mask and the washing mask. In such a case the second layercan be completely opaque. Washing away the exposed regions of thewashing mask provides that the second layer disposed in those regionscan be removed. It can advantageously be provided that the washing maskwhich has remained under the non-removed regions of the second layer issealed in relation to environmental influences by the application of aprotective layer and in that way a particularly reliable multi-layerbody is formed.

In a further advantageous configuration it can be provided that theexposure mask is joined to the multi-layer body. As already describedhereinbefore the processes according to the invention offer manydifferent possible ways of producing multi-layer bodies and the processsteps are not limited to a one-off use. If therefore firstly amulti-layer body which is in the form of an exposure mask has beenproduced, it can then be used like a conventional exposure mask forexample as an exposure mask in semiconductor manufacture. Such anexposure mask is not permanently joined to the second multi-layer bodyand can be removed after the exposure operation.

It can also be provided however that the second multi-layer body isbuilt up in layer-wise fashion on the exposure mask. If it is providedthat the exposure mask is removed after exposure or at a later time, aseparation layer can be arranged between the exposure mask and thesecond multi-layer body, which permits such release.

In a further advantageous configuration it can be provided that theexposure mask is permanently joined to the second multi-layer body andin that way a third multi-layer body is produced, which can be providedas an end product or as an intermediate product for further layer-wiseconstruction of a multi-layer body which is still more complex.

As already set forth the multi-layer bodies can involve both flexiblefilm elements and also rigid elements, for example semiconductor chipsor surfaces of electronic devices such as for example cell telephones.

The invention will be described in greater detail with reference to thedrawings in which:

FIG. 1 shows a diagrammatic view in section of a first embodiment of amulti-layer body according to the invention,

FIG. 2 shows a diagrammatic view in section of the first productionstage of the multi-layer body of FIG. 1,

FIG. 3 shows a diagrammatic view in section of the second productionstage of the multi-layer body of FIG. 1,

FIG. 4 shows a diagrammatic view in section of the third productionstage of the multi-layer body of FIG. 1,

FIG. 5 shows a diagrammatic view in section of the fourth productionstage of the multi-layer body of FIG. 1,

FIG. 5 a shows a diagrammatic view in section of a modifiedconfiguration of the production stage shown in FIG. 5,

FIG. 5 b shows a diagrammatic sectional view of the production stagefollowing that shown in FIG. 5 a,

FIG. 6 shows a diagrammatic view in section of the fifth productionstage of the multi-layer body of FIG. 1,

FIG. 7 shows a diagrammatic view in section of the sixth productionstage of the multi-layer body of FIG. 1,

FIG. 8 shows a diagrammatic view in section of the seventh productionstage of the multi-layer body of FIG. 1,

FIG. 9 shows a diagrammatic view in section of the fifth productionstage of a second embodiment of the multi-layer body of FIG. 1,

FIG. 10 shows a diagrammatic view in section of the sixth productionstage of a second embodiment of the multi-layer body of FIG. 1,

FIG. 11 shows a diagrammatic view in section of the seventh productionstage of a second embodiment of the multi-layer body of FIG. 1,

FIG. 12 shows a diagrammatic view in section of the eighth productionstage of a second embodiment of the multi-layer body of FIG. 1,

FIG. 13 shows a diagrammatic view in cross-section of a second stage ofa multi-layer body according to the invention,

FIGS. 14 a through 14 d show diagrammatic views in cross-section of theproduction steps of a third embodiment of a multi-layer body accordingto the invention,

FIG. 15 shows a schematic diagram of etching rates of a photosensitivelayer,

FIGS. 16 a and 16 b show a first example of use of a multi-layer bodyaccording to the invention, and

FIGS. 17 a through 17 d show a second example of use of a multi-layerbody according to the invention.

FIG. 1 shows a multi-layer body 100 in which arranged on a carrier film1 are a functional layer 2, a replication layer 3, a metallic layer 3 mand an adhesive layer 12. The functional layer 2 is a layer whichpredominantly serves to enhance the mechanical and chemical stability ofthe multi-layer body but which can also be designed in known manner toproduce optical effects, in which respect it can also be provided thatthe layer is formed from a plurality of partial layers. It can alsoinvolve a layer which is made from wax or which is in the form of arelease layer. It can however also be provided that that layer isomitted and the replication layer 3 is disposed directly on the carrierfilm 1. It can further be provided that the carrier film 1 itself is inthe form of a replication layer.

The multi-layer body 100 can be a portion of a transfer film, forexample a hot stamping film, which is applied to a substrate by means ofthe adhesive layer 12. The adhesive layer 12 can be a melt adhesivewhich melts under the effect of heat and permanently joins themulti-layer body to the surface of the substrate.

The carrier film 1 can be in the form of a mechanically and thermallystable film comprising PET.

Regions involving different structures can be shaped into thereplication layer 3 by means of known processes. In the illustratedembodiment these involve regions 4 having diffractive structures andreflecting regions 6.

The metallic layer 3 m disposed on the replication layer 3 hasdemetallised regions 10 d which are arranged in coincident relationshipwith the diffractive structures 4. The multi-layer body 100 appearstransparent or partially transparent in the regions 10 d.

FIGS. 2 through 8 now show the production stages of the multi-layer body100. The same components as in FIG. 1 are denoted by the samereferences.

FIG. 2 shows a multi-layer body 100 a in which the functional layer 2and the replication layer 3 are arranged on the carrier film 1.

The replication layer 3 is structured in its surface by known processessuch as for example hot stamping. For that purpose for example athermoplastic replication lacquer is applied by printing, spraying orlacquering to constitute the replication layer 3, and a relief structureis shaped into the replication lacquer by means of a heated die or aheated replication roller.

The replication layer 3 can also be a UV hardenable replication lacquerwhich is structured for example by a replication roller. The structuringhowever can also be produced by UV radiation through an exposure mask.In that way the regions 4 and 6 can be shaped into the replication layer3. The region 4 can be for example the optically active regions of ahologram or a Kinegram® security feature.

FIG. 3 now shows a multi-layer body 100 b which is formed from themulti-layer body 100 a in FIG. 2, by a procedure whereby the metalliclayer 3 m is applied to the replication layer 3 with a uniform surfacedensity, for example by sputtering. In this embodiment the metalliclayer 3 m involves a layer thickness of some 10 nm. The layer thicknessof the metallic layer 3 m can preferably be so selected that the regions4 and 6 involve a low level of transmission, for example between 10% and0.001%, that is to say an optical density of between 1 and 5, preferablybetween 1.5 and 3. Accordingly the optical density of the metallic layer3 m, that is to say the negative decadic logarithm of transmission, isbetween 1 and 3 in the regions 4 and 6. It can preferably be providedthat the metallic layer 3 m involves an optical density of between 1.5and 2.5. The regions 4 and 6 therefore appear to be opaque or reflectingto the eye of the person viewing them.

It is particularly advantageous here for the layer 3 m to be applied ina layer thickness with which the layer is substantially opaque whenapplied to a planar surface and has an optical density of greater than2. The thicker the metallic layer 3 m applied to the replication layer3, the greater is the effect of the change in the effective opticallayer thickness, which is produced by the diffractive structure providedin the regions 4, on the transmission characteristics of the metalliclayer 3 m. Investigations have shown that the change in the effectiveoptical thickness of the metallic layer 3 m, caused by the diffractivestructure, is approximately proportional to the vapor-deposited layerthickness and thus approximately proportional to the optical density. Asthe optical density represents the negative logarithm of transmission,the difference in transmission between the regions 4 and 6 isover-proportionally increased in that fashion by an increase in thesurface application in respect of metallic material.

It will be noted however that the optical densities of the metalliclayer 3 m differ in the regions 4 and 6 in such a way that it is reducedin the regions 4 in relation to the regions 6. The responsibility forthat lies with the increase in surface area in the regions 4 because ofthe depth-to-width ratio of the structure elements, which is differentfrom zero, and the thickness which is reduced thereby of the metalliclayer. The dimension-less depth-to-width ratio and the spatial frequencyare characterising features for the increase in surface area ofpreferably periodic structures. Such a structure forms ‘peaks’ and‘troughs’ in a periodic succession. The spacing between a ‘peak’ and a‘trough’ is referred to here as the depth while the spacing between two‘peaks’ is referred to as the width. Now, the higher the depth-to-widthratio, the correspondingly steeper are the ‘peak flanks’ and thecorrespondingly thinner is the metallic layer 3 m deposited on the ‘peakflanks’. That effect is also to be observed when the situation involvesdiscretely distributed ‘troughs’ which can be arranged relative to eachother at a spacing which is a multiple greater than the depth of the‘troughs’. In such a case the depth of the ‘trough’ is to be related tothe width of the ‘trough’ in order to correctly describe the geometry ofthe ‘trough’ by specifying the depth-to-width ratio.

When producing regions of a reduced optical density, it is important toknow and appropriately select the individual parameters in respect oftheir dependencies. The degree of the reduction in optical density canvary in dependence on the substrate, the lighting and so forth. In thatrespect an important part is played by the absorption of light in themetal layer. By way of example chromium and copper reflect much lessunder some circumstances.

Table 1 shows the ascertained degree of reflection of metal layers ofAg, Al, Au, Cr, Cu, Rh and Ti, arranged between plastic films(refractive index n=1.5) at a light wavelength λ=550 nm. In this casethe thickness ratio ∈ is formed as the quotient of the thickness t ofthe metal layer, which is required for the degree of reflection R=80% ofthe maximum R_(Max) and the thickness required for the degree ofreflection R=20% of the maximum R_(Max).

TABLE 1 t for 80% t for 20% Metal R_(Max) R_(Max) R_(Max) ε h/d Ag 0.94431 nm   9 nm 3.4 1.92 Al 0.886 12 nm 1.5 nm 4.8 2.82 Au 0.808 40 nm  12nm 3.3 1.86 Rh 0.685 18 nm 4.5 nm 4.0 2.31 Cu 0.557 40 nm  12 nm 3.31.86 Cr 0.420 18 nm   5 nm 3.6 2.05 Ti 0.386 29 nm 8.5 nm 3.3 1.86

From the point of view of heuristic consideration silver and gold (Agand Au), as can be seen, have a high maximum degree of reflectionR_(Max) and require a relatively small depth-to-width ratio to reducethe optical density of the metallic layer, in the foregoing example toproduce transparency. Aluminum (Al) admittedly also has a high maximumdegree of reflection R_(Max), but it requires a higher depth-to-widthratio. It can preferably therefore be provided that the metal layer isformed from silver or gold. It can however also be provided that themetal layer is formed from other metals or from metal alloys.

Table 2 now shows the calculation results obtained from strictdiffraction calculations for relief structures with differentdepth-to-width ratios, which are in the form of linear, sinusoidalgratings with a grating spacing of 350 nm. The relief structures arecoated with silver of a nominal thickness t₀=40 nm. The light whichimpinges on the relief structures is of the wavelength λ=550 nm (green)and is TE-polarised or TM-polarised.

TABLE 2 Degree of Degree of Depth- Grating Degree of trans- Degree oftrans- to-width spacing Depth reflection parency reflection parencyratio in nm in nm (0R) TE (0T) TE (0R) TM (0T) TM 0 350 0 84.5% 9.4%84.5% 9.4% 0.3 350 100 78.4% 11.1% 50.0% 21.0% 0.4 350 150 42.0% 45.0%31.0% 47.0% 1.1 350 400 2.3% 82.3% 1.6% 62.8% 2.3 350 800 1.2% 88.0%0.2% 77.0%

As was found, in particular the degree of transparency or transmissionapart for the depth-to-width ratio is dependent on the polarisation ofthe radiated light. That dependency is shown in Table 2 for thedepth-to-width ratio d/h=1.1. It can be provided that that effect is putto use for the selective formation of further layers.

It was further found that the degree of transparency or the degree ofreflection of the metal layer 3 m is wavelength-dependent. That effectis particularly highly pronounced for TE-polarised light.

It was further found that the degree of transparency or transmissiondecreases if the angle of incidence of the light differs from the normalangle of incidence, that is to say the degree of transparency decreasesif the light is not perpendicularly incident. That signifies that themetal layer 3 m can be transparent or less opaque than in the reflectingregions 6, only in a restricted cone of incidence of the light. It cantherefore be provided that the metal layer 3 m is opaque whenilluminated inclinedly, in which respect that effect can also be usedfor the selective formation of further layers.

Besides the depth-to-width ratio of a structure, the change in opticaldensity is also influenced by the spatial frequency of the structure.Thus it has further been found that a change in the transparentcharacteristics of a layer applied to a structure can be achieved if theproduct of spatial frequency and relief depth is greater in a firstregion of the structure than the product of spatial frequency and reliefdepth in a second region of the structure.

The production of regions of differing transparency or transmissionhowever can also be achieved by other effects, for example by

-   -   polarisation dependency of the level of transmission as a        consequence of differently oriented structures;    -   the form factor of the structures, that is to say structures of        a rectangular, sinusoidal, sawtooth or other profile can involve        a different level of transmission with the same product of        spatial frequency and relief depth; and    -   directed vapor deposition of the first layer in combination with        special structures or structure combinations or structure        arrangements.

If the first structure is a structure involving a stochastic profile,for example a matt structure, correlation length, roughness depth andstatistical distribution of the profile can be typical parameters whichinfluence transmission.

Thus, to produce regions involving differing transparency ortransmission, it is also possible to use relief structures which differin one or more of the above-stated parameters, in the first region andin the second region.

FIG. 4 shows a multi-layer body 100 c formed from the multi-layer body100 b shown in FIG. 3 and a photosensitive layer 8. This can be anorganic layer which is applied by conventional coating processes such asintaglio printing in fluid form. It can also be provided that thephotosensitive layer is applied by vapor deposition or is applied bylamination in the form of a dry film.

The photosensitive layer 8 can be for example a positive photoresistsuch as AZ 151.2 or AZ P4620 from Clariant or S1822 from Shipley whichis applied to the metal layer 3 m in a surface density of 0.1 g/m² to 50g/m². The layer thickness depends on the desired resolution and theprocedure. Thus lift-off procedures involve rather thicker layers of alayer thickness of >1 μm, corresponding to a surface density of about 1g/m². Preferred weights in relation to surface area are in the range ofbetween 0.2 g/m² and 10 g/m².

The application can be over the entire surface area. It is however alsopossible to provide for application in partial regions, for example inregions arranged outside the above-mentioned regions 4 and 6. This caninvolve regions which have to be arranged only relatively coarsely inregister relationship with the design, for example decorative graphicrepresentations such as for example random patterns or patterns formedfrom repeated images or texts.

FIG. 5 now shows a multi-layer body 100 d which is formed by exposure ofthe multi-layer body 100 c in FIG. 4 through the carrier film 1. UVlight 9 can be provided for the exposure operation. Because now, asdescribed hereinbefore, the regions 4 provided with diffractivestructures having a depth-to-width ratio of greater than zero have alower optical density than the reflecting regions 6, the UV irradiationoperation produces in the photosensitive layer 8 regions 10 which havebeen more greatly exposed and which differ from less exposed regions 11,in terms of their chemical properties.

The embodiment shown in FIG. 5 involves homogeneous illumination whichis of equal intensity in all regions of the multi-layer body 100 d. Itis however also possible to provide for partial illumination, forexample

a) to leave structures with a high depth-to-width ratio as designelements and not to demetallise them;

b) to introduce an additional item of information, for example through amask in strip form, which moves with the multi-layer body 100 d duringthe exposure operation,

c) to introduce an individual item of information such as for example aserial number. It can be provided in that respect that an identificationis introduced by way of short-term exposure by means of a programmablespatial light modulator or a controlled laser. In that way thereforedemetallised regions are only formed there, in which the depth-to-widthratio is appropriate and in which the alphanumeric identification isprovided.

The wavelength and the polarisation of the light as well as the angle ofincidence of the light are illumination parameters which make itpossible to specifically emphasise and selectively process structures.

Chemical properties can also be used for that purpose. The regions 10and 11 can differ for example by virtue of their solubility in solvents.In that way the photosensitive layer 8 can be ‘developed’ after theexposure operation with UV light, as is further shown in FIG. 6.‘Development’ of the photosensitive layer produces a visible image inmask form of the metallic layer 3 m produced with regions of differentoptical density, from the latent image produced by exposure in thephotosensitive layer, by the removal of regions.

If a depth-to-width ratio of >0.3 is usually provided in the regions 4to produce a transparency which is visible to the human eye, it hassurprisingly been found that the depth-to-width ratio which is adequatefor development of the photosensitive layer can be substantially less.There is also no need for the metallic layer 3 m to be so thin that theregions 4 appear transparent when considered visually. Thevapor-deposited carrier film can therefore be opaque, for the reducedtransparency can be compensated by an increased exposure dose in respectof the photosensitive layer 8. It is further to be borne in mind thatexposure of the photosensitive layer is typically provided in the nearUV range so that the visual viewing impression is not crucial in termsof assessing optical density.

FIGS. 5 a and 5 b show a modified embodiment. The photosensitive layer 8shown in FIG. 5 is not provided in the multi-layer body 100 d′ in FIG. 5a. Instead there is a replication layer 3′ which is a photosensitivewashing mask. The multi-layer body 100 d′ is exposed from below,whereby, in the more greatly exposed regions 100, the replication layer3′ is changed in such a way that it can be washed off.

FIG. 5 b now shows a multi-layer body 100 d″ which functionallycorresponds to the multi-layer body shown hereinafter in FIG. 8. It willbe noted however that not just the metallic layer 3 m is removed withthe washing process in the regions 10, but also the replication layer3′. That provides that transparency is produced in those regions, inrelation to the multi-layer body shown in FIG. 8, and fewer productionsteps are required.

FIG. 6 shows the ‘developed’ multi-layer body 100 e which is formed fromthe multi-layer body 100 d by the action of a solvent applied to thesurface of the exposed photosensitive layer 8. That now produces regions10 e in which the photosensitive layer 8 is removed. The regions 10 eare the regions 4 described with reference to FIG. 3, with adepth-to-width ratio of greater than zero of the structure elements. Thephotosensitive layer 8 is retained in regions 11 because they involvethe regions 6 which are described with reference to FIG. 3 and in whichthe structure elements have a depth-to-width ratio of equal to zero.

In the embodiment shown in FIG. 6 the photosensitive layer 8 is formedfrom a positive photoresist. When using such a photoresist the exposedregions are soluble in the developer. In contrast thereto when using anegative photoresist the unexposed regions are soluble in the developer,as is described hereinafter in the embodiment shown in FIGS. 9 through12.

Now, as shown by reference to a multi-layer body 100 f in FIG. 7, themetallic layer 3 m can be removed in the regions 10 e which are notprotected from the attack of the etching agent by the developedphotosensitive layer serving as the etching mask. The etching agent canbe for example an acid or a lye. The demetallised regions 10 d alsoshown in FIG. 1 are produced in that fashion.

In that way therefore the metallic layer 3 m can be demetallised inaccurate register relationship without involving additionaltechnological complication. No complicated and expensive precautionshave to be taken for that purpose, such as for example when applying anetching mask by mask exposure or printing. When such a conventionalprocess is involved tolerances of >0.2 mm are usual. In contrast, withthe process according to the invention tolerances in the μm range intothe nm range are possible, that is to say tolerances which are governedonly by the replication process selected for structuring of thereplication layer and the origination.

It can be provided that the metallic layer 3 m is in the form of asuccession of different metals and the differences in the physicaland/or chemical properties of the metallic partial layers are put touse. It can be provided for example that aluminum is deposited as thefirst metallic partial layer, having a high level of reflection andtherefore causing reflecting regions to be clearly evident when themulti-layer body is viewed from the carrier side. The second metallicpartial layer deposited can be chromium which has a high level ofchemical resistance to various etching agents. The etching operation forthe metallic layer 3 m can now be implemented in two stages. It can beprovided that the chromium layer is etched in the first stage, in whichcase the developed photosensitive layer 8 is provided as the etchingmask, and then in the second stage the aluminum layer is etched, inwhich case the chromium layer now acts as the etching mask. Suchmulti-layer systems permit a greater degree of flexibility in the choiceof the materials used in the production procedure for the photoresist,the etching agent for the photoresist and the metallic layer.

FIG. 8 shows the optional possibility of removing the photosensitivelayer after the production step shown in FIG. 7. FIG. 8 illustrates amulti-layer body 100 g formed from the carrier film 1, the functionallayer 2, the replication layer 3 and the structured metallic layer 3 m.

The multi-layer body 100 g can be converted into the multi-layer body100 shown in FIG. 1 by subsequently applying the adhesive layer 12.

FIG. 9 now shows a second embodiment of a multi-layer body 100 e inwhich the photosensitive layer 8 is formed from a negative photoresist.As can be seen from FIG. 9 a multi-layer body 100 e′ has regions 10 e′in which the unexposed photosensitive layer 8 is removed by development.The regions 10 e′ involve opaque regions of the metallic layer 3 m (seereference 6 in FIG. 3). The exposed photosensitive layer 8 is notremoved in regions 11, that involves less opaque regions of the metalliclayer 3 m (see reference 4 in FIG. 3), that is to say regions of loweroptical density than the regions 10 e′.

FIG. 10 shows a multi-layer body 100 f′ formed by removal of themetallic layer 3 m by an etching process from the multi-layer body 100e′ (FIG. 9). For that purpose the developed photosensitive layer 8 isprovided as the etching mask which is removed in the regions 10 e′ (FIG.9) so that the etching agent there breaks down the metallic layer 3 m.That results in the formation of regions 10 d′ which no longer have ametallic layer 3 m.

As shown in FIG. 11 a multi-layer body 100 f″ is now formed from themulti-layer body 100 f′, having a second layer 3 p which covers theexposed replication layer 3 in the regions 10 d′. The layer 3 p can be adielectric such as TiO₂ or ZnS, or a polymer. Such a layer can be forexample vapor-deposited over a surface, in which respect it can beprovided that the layer is formed from a plurality of mutuallysuperposed thin layers which can differ for example in their refractiveindex and which in that way can produce color effects in the lightshining thereon. A thin layer having color effects can be formed forexample from three thin layers with a high-low-high-index configuration.The color effect appears less striking in comparison with metallicreflecting layers, which is advantageous for example if patterns are tobe produced on passports or identity cards in that way. The patterns canappear to the viewing person for example as transparent green or red.

Polymer layers can be for example in the form of organic semiconductorlayers. In that way an organic semiconductor component can be formed bya combination with further layers.

FIG. 12 now shows a multi-layer body 100 f′″ formed from the multi-layerbody 100 f″ (FIG. 11) after removal of the remaining photosensitivelayer. That can involve a ‘lift-off’ procedure. In that way the secondlayer 3 p applied in the previous step is there removed again at thesame time. Therefore, adjacent regions with layers 3 p and 3 m are nowformed on the multi-layer body 100 f′″, which can differ from each otherfor example in their optical refractive index and/or their electricalconductivity.

It can be provided that the metallic layer 3 m is galvanicallyreinforced and in that way the regions 11 are for example in the form ofregions affording particularly good electrical conductivity.

It can also be provided that the regions 11 are transparent and for thatpurpose the metallic layer 3 m is removed by etching. It is possible toprovide an etching agent which does not attack the layer 3 p applied inthe other regions. It can however also be provided that the etchingagent is caused to act only until the metallic layer is removed.

It can further be provided that there is then applied to the multi-layerbody 100 f′″ (FIG. 12) a third layer which can be formed from adielectric or a polymer. That can be done with the process stepsdescribed hereinbefore, by a procedure whereby once again aphotosensitive layer is applied, which after exposure and developmentcovers the multi-layer body 100 f′″ outside the regions 11. The thirdlayer can now be applied as described hereinbefore and then the remainsof the photosensitive layer are removed and thus at the same time thethird layer is removed in those regions. In that way for example layersof organic semiconductor components can be structured in a particularlyfine fashion and in accurate register relationship.

FIG. 13 now shows a multi-layer body 100′ which is formed from themulti-layer body 100 f′″ (FIG. 12) by the addition of the adhesive layer12 shown in FIG. 1. The multi-layer body 100′ has been produced, likethe multi-layer body 1 shown in FIG. 1, by using the same replicationlayer 3. It is therefore possible with the process according to theinvention to produce multi-layer bodies of differing configurations,starting from a unitary layout.

The process according to the invention can be further developed withoutadverse effects in terms of quality in order to structure further layersin accurate register relationship. For that purpose it can be providedthat further optical effects such as total reflection, polarisation andspectral transparency of the previously applied layers are used to formregions of differing optical density in order to produce exposure masksinvolving accurate register relationship.

It can also be provided that different local absorption capability isafforded by mutually superposed layers and exposure or etching masks areproduced by laser-supported thermal ablation.

FIGS. 14 a through 14 d now show by reference to an embodiment by way ofexample how the metallic layer 3 m arranged in the regions 11 can beremoved in accurate register relationship from the multi-layer body 100f′″ shown in FIG. 12 and can be replaced in accurate registerrelationship by a non-metallic layer 3 p′. The layer 3 p′ can be adielectric layer which differs in its optical refractive index from thelayer 3 p.

FIG. 14 a shows a multi-layer body 100 g in which the metallic layer 3 min the regions 4 is such that it has a different optical density inrelation to the layer 3 p in the regions 6. A photosensitive layer 8covers over the regions 3 p and 3 m disposed on the replication layer 3.

FIG. 14 b now shows a multi-layer body 100 g′ obtained by exposure anddevelopment of the photosensitive layer 8, as described hereinbeforewith reference to FIGS. 5 and 6. The regions 11 covered with thedeveloped photosensitive layer form an etching mask so that the metalliclayer 3 m can be removed by etching in the regions 10 e in which thephotosensitive layer is removed after the development operation.

FIG. 14 c shows after a further process step a multi-layer body 100 g″on which a layer 3 p′ which for example can be in the form of adielectric is applied over the full surface area involved. The layer 3p′ can also be in the form of a thin-layer system comprising a pluralityof successively applied layers, whereby the layer 3 p′ can produce colorchange effects in known manner.

FIG. 14 d now shows a multi-layer body 100 g′″ after removal of theremains of the photosensitive layer 8 and the regions arranged thereonof the layer 3 p′, which multi-layer body 100 g′″ can be made into acomplete multi-layer body for example by the addition of an adhesivelayer as described hereinbefore with reference to FIG. 13.

On the replication layer 3 the multi-layer body 100 g′″ has regionswhich are covered with the layer 3 p and regions which are covered withthe layer 3 p′.

As the layers 3 p and/or 3 p′ can be thin-layer systems, they canproduce color change effects, as already described hereinbefore. In thatrespect it can be provided for example that the layer 3 p which in theembodiment in FIG. 14 d covers over the regions of the replication layer3 with a depth-to-width ratio of greater than zero, is in the form of athin-layer system. It is possible in that way for filigree patterns suchas guilloche patterns to be in the form of security features whichunobtrusively stand out from their surroundings and still clearlyvisibly show representations disposed therebeneath.

The process described with reference to FIGS. 14 a through 14 d can beused for applying further layers. Because the layers 3 p and 3 p′ arethin layers of the order of magnitude of some μm or nm, the structuresintroduced into the replication layer 3 are retained so that for exampleit is possible to apply a further metallic layer which in the regions ofthe replication layer 3 with a depth-to-width ratio of greater than zeroinvolves a lower optical density than in the regions with adepth-to-width ratio equal to zero. In that way the further metalliclayer can be used as a mask layer which can be partially removed withthe above-described process steps or which can be provided as atemporary intermediate layer in order to apply one or more non-metalliclayers in accurate register relationship.

The process according to the invention includes the possibility, forforming masks, of providing regions which both have a depth-to-widthratio of greater than zero but which is of differing values, whereby theoptical density of the regions coated with the same surface rate isdifferent.

FIG. 15 now shows a diagrammatic graphic representation of three etchingcharacteristics of developers which are intended for producing theetching mask from the photosensitive layer. The etching characteristicsrepresent the etching rate, that is to say the removal of material perunit of time, in dependence on the energy density with which thephotosensitive layer was exposed. A first etching characteristic 150 lis linear. Such an etching characteristic can be preferred ifdevelopment is effected in accordance with time.

In general however a binary etching characteristic 150 b can bepreferred because only minor differences are required in the energydensity in order to produce a markedly different etching rate and inthat way, with slight differences in the optical density of adjacentregions, to implement complete removal of the mask layer in the regionsinvolving a higher depth-to-width ratio or vice-versa, with a high levelof certainty.

A third etching characteristic 150 g involving a bell-shapedconfiguration which can be adjusted by the choice of the photoresist andthe process implementation can be used in order to remove or obtainstructures selectively in dependence on the optical density of theregion. That etching characteristic can be particularly preferred whenfor example there are three regions involving a differing opticaldensity.

FIGS. 16 a and 16 b now show a first example of use involving amulti-layer body 160 according to the invention. It can be arranged forexample on the front side of an ID card 162. The multi-layer body 160 isprovided with a metallic layer which is partially removed in registerrelationship and which covers over diffractive structures and which isin the form of guilloche patterns 166 g, 166 g′ and 166 g″, star-shapedelements 166 s and alphanumeric characters 166 a and 166 a′. In thatrespect FIGS. 16 a and 16 b show different views of the multi-layer body160, which are produced by pivoting the ID card 162. The guillochepatterns 166 g are fine regions in line form, which retain theirposition upon pivoting movement of the ID card 162. The guillochepatterns 166 g′ and 166 g″ are fine regions in line form, which becomevisible in succession upon pivoting movement of the ID card 162 so thatthe illusion of a movement is produced. The star-shaped elements 166 sand 166 s′ are configurations of a region with a holographic structureso that they involve a differing size and/or color depending on therespective tilted position of the ID card 162. The alphanumericcharacters 166 a and 166 a′ can involve for example a region having aKinegram® structure.

FIGS. 17 a through 17 d show a second example of use of a multi-layerbody according to the invention. A first multi-layer body 20 is in theform of an exposure mask in this example of use. As shown in FIG. 17 athe first multi-layer body 20 comprises a carrier film 1 with areplication layer 30 coated with a partially shaped metallic layer 30 m.The first multi-layer 20 can preferably have been produced with theprocesses described hereinbefore.

As shown in FIG. 17 a the first multi-layer body 200 is disposed on asecond multi-layer body 170 a which is formed from a carrier film 31, ametallic layer 31 m and a photosensitive layer 8. The outside of themetallic layer 30 m of the first multi-layer body 200 faces towards theoutside of the carrier film 31 and bears thereagainst. The metalliclayer 30 m is removed in regions 40 in which, as described hereinbefore,the replication layer 30 is of a greater depth-to-width ratio than inthe regions in which the metallic layer 30 m is not removed.

In the example of use shown in FIG. 17 a the second multi-layer body 170a is exposed through the first multi-layer body 200 which is in the formof an exposure mask. Exposure is indicated by arrows 9. Because of theextremely small layer thicknesses of the carrier film 31 and themetallic layer 31 m, the image of the partial, metallic layer 31 m isnow transferred on to the photosensitive layer 8, whereby, as shown inFIG. 17 b, a multi-layer body 170 b is produced in which thephotosensitive layer 8 has regions 8 b which have been more greatlyexposed. As has been found, in that case the metallic layer 31 marranged in the beam path can be opaque. The opaque metallic layer 31 madmittedly reduces the illumination strength produced on thephotosensitive layer 8, but it does not interfere with the production ofmore greatly exposed regions 8 b. As already stated the metallic layer31 m is of a small layer thickness so that imaging errors for exampledue to scatter are not to be observed.

FIG. 17 c now shows a multi-layer body 170 c which is formed bydevelopment of the photosensitive layer 8 from the multi-layer body 170b in FIG. 17 c. In this example of use the photosensitive layer 8 is aso-called negative photoresist in which unexposed regions are removed bydevelopment.

FIG. 17 d finally shows a multi-layer body 170 which is formed byetching of the metallic layer 31 m and removal of the remains of thephotosensitive layer 8, from the multi-layer body 170 c of FIG. 17 c.The metallic layer 31 m is produced in the regions which were covered bythe developed photosensitive layer 8. It can form on the multi-layerbody 170 for example an electrical component such as an antenna and/or acoil, or one or more conductor tracks.

Although in this example of use register accuracy cannot be set withoutadjustment, nonetheless it is advantageously possible to producefiligree patterns which in their partial regions are oriented inaccurate register relationship with each other. It can however also beprovided that orientation in accurate register relationship is dispensedwith, if for example the multi-layer body 170 forms a security featuresuch as a guilloche pattern covering over a security document, whichdoes not have to be oriented in accurate register relationship in orderto perform the security function.

It can further be provided that the regions 40 are differentiated inrespect of their depth-to-width ratio and/or their polarisationdependency and in that way it is possible to form a lithographic grayscale mask which can be of very small thickness. Conventional glassmasks cannot be thinner than 5 μm, which can limit the applicabilitythereof.

1-25. (canceled)
 26. A multi-layer body having a replication layer andat least one partially shaped first layer arranged on the replicationlayer, wherein a diffractive first relief structure is shaped in a firstregion of the replication layer, the first relief structure is notshaped in the replication layer in a second region of the replicationlayer, and the first layer is partially removed in a manner determinedby the arrangement of the first relief structure so that the first layeris removed in accurate register relationship with the first reliefstructure in the first region but not in the second region or in thesecond region but not in the first region, wherein the first layer inthe first region is in the form of lines and/or dots of a width and/or adiameter in the region of between 200 nm and 5 μm.
 27. A multi-layerbody as set forth in claim 26, wherein the second region is shaped inpattern form and the first region and the second region are arranged indirectly mutually adjacent juxtaposed relationship, wherein the secondregion is enclosed by the first region or the first region is enclosedby the second region.
 28. A multi-layer body as set forth in claim 26,wherein the second region comprises two or more partial regions enclosedby the first region, an optically active second relief structure isshaped in the replication layer in the second region and the first layeris a reflection layer which is removed in the first region and thusarranged in accurate register relationship with the second reliefstructure.
 29. A multi-layer body as set forth in claim 26 wherein thefirst region comprises two or more partial regions enclosed by thesecond region or vice versa, and the first layer is a reflection layerwhich is removed in the second region and thus arranged in accurateregister relationship with the first relief structure.
 30. A multi-layerbody as set forth in claim 28, wherein the partial regions of the secondregion are of a width of less than 2 mm.
 31. A multi-body as set forthin claim 26, wherein a second layer is arranged in the regions of thereplication layer in which the first layer is not present.
 32. Amulti-layer body as set forth in claim 26, wherein the first layerand/or the second layer is/are formed from a dielectric.
 33. Amulti-layer body as set forth in claim 32 wherein the first layer andthe second layer have different refractive indices.
 34. A multi-layerbody as set forth claim 26, wherein in the first layer and/or the secondlayer is/are formed from a polymer.
 35. A multi-layer body as set forthin claim 26 wherein the first layer and/or the second layer is/are inthe form of a colored layer.
 36. A multi-layer body as set forth inclaim 26, wherein the first layer and/or the second layer is/are formedfrom a plurality of partial layers.
 37. A multi-layer body as set forthin claim 36 wherein the partial layers form a thin film layer system.38. A multi-layer body as set forth in claim 36 wherein the partiallayers are formed from different materials.
 39. A multi-layer body asset forth in claim 26, wherein the first layer and/or the second layerforms/form an optical pattern.
 40. A multi-layer body as set forth inclaim 26, wherein the first layer and/or the second layer forms/form araster image.
 41. A multi-layer body as set forth in claim 26, whereinthe first layer and/or the second layer form one or more opticalsecurity features.
 42. A multi-layer body as set forth in claim 26,wherein the first layer and/or the second layer form or forms anelectronic component.
 43. A multi-layer body as set forth in claim 26,wherein the multi-layer body is a transfer film, a hot stamping film ora laminating film.
 44. A multi-layer body as set forth in claim 26,wherein the first layer and/or the second layer form an orientationlayer for the orientation of liquid crystals.
 45. A multi-layer body asset forth in claim 44 wherein the orientation layer has diffractivestructures for the orientation of the liquid crystals, which are locallydifferently oriented so that when viewed under polarised light theliquid crystals represent an item of information. 46-53. (canceled)